The fundamentals of maintaining and augmenting human and animal cells in cell cultures have been systematically developed during the last twenty years. Methods for cultivating cells have now been firmly established for the production of vaccine substances, antibodies, interferon, enzymes, and hormones in many laboratories.
Primary cells and diploid cells require a solid substrate having a distinct surface charge for their growth. These cells are designated as "anchorage-dependent" cells since they are only able to grow if they can adhere to a carrier.
Initially, glass in the form of Petri dishes, culture bottles, or roll-culture flasks was used as the carrier. However, there can be formed only a monolayer on the surfaces of the equipment so that the surface available per unit will be limited. Thus, for such cell augmentation cultures on a commercial scale, thousands of roll-culture flasks have to be cleaned, sterilized, filled with nutrient medium, inoculated with cells, and harvested once the cell augmentation is finished. Since all of these steps have to be carried out under sterile conditions, they are very labor- and cost-intensive.